Palm Diversity Research Articles

Genetic diversity and structure of Tunisian and Indian date palm (Phoenix dactylifera and sylvestris) cultivars and genotypes revealed by AFLP markers

The date palm breeding programs need to discover valid genetic fingerprints to characterize cultivars and assess their genetic diversity. This study assessed the genetic diversity among thirty-nine date palm cultivars from Tunisia (Phoenix dactylifera) and India (Phoenix sylvestris) by using six AFLP (Amplified Fragment Length Polymorphism) markers. 360 loci were amplified, with 127 loci polymorphic (34.35 %). The Jaccard's similarity coefficient ranged from 0.161 to 0.931, with the mean genetic distances of 0.568. AFLP's average marker index value was 7.28, with a resolving power of 10.91. The analysis of population structure showed two main clusters with a clear separation between Tunisian and Indian cultivars.Furthermore, the heatmap analysis allowed the identification of 10 bands specific to the Indian accessions, which were not detected in Tunisian genotypes. These loci could be linked to genes involved in adapting the species in Indian lands, which allowed the study of the genetic diversity of date palm resources of different origins, confirming the existence of at least two origins of domestication. Additionally, identifying AFLP loci specific to P. dactylifera and P. sylvestris will significantly contribute to breeding programs by exploiting species-specific polymorphisms.

Determining Priority Conservation of Endemic Palms in the Philippine Islands Using a Localized Conservation Priority Index

The mass production of palms for economic and cultural use in the Philippines leads to risk of extinction, genetic erosion, and biodiversity loss. This study aimed to identify top-priority endemic Arecaceae species in the Philippine Islands using a modified localized conservation priority index (LCPI), which considered factors such as distribution, harvesting risk, and economic and cultural use. A taxonomic list of 89 species was constructed, spanning 12 genera, with Calamus being the most speciose genus containing 25 endemic species. The LCPI assessment designated 31 high priority species for conservation, 24 as medium priority, and 34 as low priority. High-priority palms scored highly on the LCPI due to their limited distribution, high susceptibility to overharvesting, and significant economic and cultural value to local communities. The study reveals the diversity and importance of endemic Philippine palms needing urgent conservation efforts to sustain their valuable ecosystem services.

TROPICAL PALMS AND FACTORS INFLUENCING THEIR DISTRIBUTIONS AND DIVERSITY, WITH A FOCUS ON Pinanga DIVERSITY IN SOUTHEAST ASIA

ARTICLE HIGLIGHTS- The palm genus Pinanga is the most diverse in Southeast Asia. - Limited ecological studies on Pinanga show the influence of environmental factors.- High Pinanga endemism in Borneo requires conservation action.ABSTRACTPalms represent some of the keystone species in tropical forests, providing numerous ecosystem services. They are widely studied by botanists because of their iconic and majestic appearance, although ecological studies of palm abundance, distributions, and diversity have only recently begun to gain attention. The abundance and diversity of palms at different spatial scales can be influenced by various factors, such as climate, soil properties, hydrology, topography and forest structure; understanding these influences is essential for conservation. This review details four abiotic factors (climate, soil chemistry, hydrology and topography) and one biotic factor (forest structure) affecting palm distribution and diversity. The genus Pinanga, one of the most diverse genera of palms, is discussed in terms of its distribution and diversity in Southeast Asia. Ecological studies on Pinanga diversity in the region are examined, revealing the influence of micro- and macro-scale variation in environmental factors, such as litter depth and thickness, canopy openness and crown cover, elevation, slope, aspect, light intensity, humidity and air temperature. The existing knowledge gaps on Pinanga ecology in Southeast Asia are discussed, and the need for more studies on population structures, functional traits and determinants of Pinanga diversity and distributions within different lowland forest types in the region are highlighted. The high endemism shown by Pinanga necessitates a more comprehensive ecological understanding of this genus to better inform its conservation and protection.

Hybridization in palms (Arecaceae).

Hybridization has significant evolutionary consequences across the Tree of Life. The process of hybridization has played a major role in plant evolution and has contributed to species richness and trait variation. Since morphological traits are partially a product of their environment, there may be a link between hybridization and ecology. Plant hybrid species richness is noted to be higher in harsh environments, and we explore this hypothesis with a keystone tropical plant lineage, palms (Arecaceae). Leveraging a recent literature review of naturally occurring palm hybrids, we developed a method to calculate hybrid frequency, and then tested if there is phylogenetic signal of hybrids using a phylogeny of all palms. Further, we used phylogenetic comparative methods to examine the interaction between hybrid frequency and presence in dry environments, on islands, and the species richness of genera. Phylogenetic generalized least squares models had stronger support than models of random association, indicating phylogenetic signal for the presence of hybrids in dry and island environments. However, all p-values were >.05 and therefore the correlation was poor between hybridization and the trait frequencies examined. Presence in particular environments are not strongly correlated to hybrid frequency, but phylogenetic signal suggests a role in its distribution in different habitats. Hybridization in palms is not evenly distributed across subfamilies, tribes, subtribes yet plays an important role in palm diversity, nonetheless. Increasing our understanding hybridization in this economically and culturally important plant family is essential, particularly since rates are projected to increase with climate change, reconfiguring the dynamics and distribution of biodiversity.

Diversity and conservation status of palms (Arecaceae) in two hotspots of biodiversity in Colombia and Ecuador

Societal Impact StatementPalms provide vital plant resources and ecosystem services to people across the tropics. To improve conservation guidance, a “health check” of palms in two highly threatened biodiversity hotspots in Colombia and Ecuador was undertaken. Palms are very diverse in these regions, but over one third are threatened with extinction now, especially among endemic species. Widespread and useful palms are also under intense human pressure and need to be prioritized in terms of sustainable management practices. Given the importance of palms for humans, inclusive conservation actions should be continued in both countries in order to safeguard this resource.Summary Palms provide central plant resources to societies in the tropics, especially in the Global South. The western Pacific and Andean regions of Colombia and Ecuador host two hotspots of biodiversity. To prioritize conservation policies towards palms, we undertook a conservation assessment of species in the region. We compiled a taxonomically verified database of specimens collected in both hotspots. We inferred preliminary conservation assessments using International Union for Conservation of Nature (IUCN) Criteria B. In addition, we evaluated the level of exposure of palms to human use and population density using the anthrome concept. We documented 144 native palm species in 33 genera occurring in both hotspots of Colombia and Ecuador. Of these, 55 are endemic to this region. We recorded 133 species for Colombia, 43 endemic, and 71 species for Ecuador, 9 endemic. A third of all palm species in the region are potentially threatened with extinction (50/144) and 12 as preliminary Critically Endangered. Aiphanes and Geonoma have the highest number of threatened species. In total, 60% of palm specimens were collected in the “low human impact” anthrome type. In contrast, 41% of specimens occur in high human density areas. The two hotspots of biodiversity in Colombia and Ecuador are very diverse in palms. However, we show that this diversity is under threat and is predominantly found in areas impacted by human activities. Extinction risk is highest in endemic species in both countries. Widespread and useful palm species also face threats linked to overexploitation or habitat loss. Inclusive conservation measures should be designed to conserve, together with communities, this plant resource.

Phylogeny, biogeography and ecological diversification of New Caledonian palms (Arecaceae).

The geographic origin and evolutionary mechanisms underpinning the rich and distinctive New Caledonian flora remain poorly understood. This is due to the complex geological past of the island and to the scarcity of well-resolved species-level phylogenies. Here, we infer phylogenetic relationships and divergence times of New Caledonian palms, which comprise 40 species. We use this framework to elucidate the biogeography of New Caledonian palm lineages, and to explore how extant species may have formed. A phylogenetic tree including 37 New Caledonian palm species and 77 relatives from tribe Areceae was inferred from 151 nuclear genes obtained by targeted sequencing. Fossil-calibrated divergence times were estimated, and ancestral ranges were inferred. Ancestral and extant ecological preferences in terms of elevation, precipitation and substrate were compared between New Caledonian sister species to explore their possible roles as drivers of speciation. New Caledonian palms form four well-supported clades, inside which relationships are well resolved. Our results support the current classification, but suggest that Veillonia and Campecarpus should be resurrected, and fail to clarify whether Rhopalostylidinae is sister to or nested in Basseliniinae. New Caledonian palm lineages derive from New Guinean and Australian ancestors, which reached the island through at least three independent dispersal events between the Eocene and Miocene. Palms then dispersed out of New Caledonia at least five times, mainly towards Pacific islands. Geographic and ecological transitions associated with speciation events differed across time and genera. Substrate transitions were more frequently associated with older than younger events. Neighbouring areas and a mosaic of local habitats shaped New Caledonia's palm flora, and the island played a significant role in generating palm diversity across the Pacific region. This new spatio-temporal framework will enable population-level ecological and genetic studies to further unpick the mechanisms underpinning New Caledonian palm endemism.

F1 Hybrids in oil palm

F1 Hybrid production in oil palm (Elaeis guineensis) is a reality. F1 Hybrids have the potential to provide massive increases in yield as demonstrated in a range of crops. Verdant has the intellectual property and “know-how” to produce haploids and double them to give doubled haploids. Doubled haploids are fertile and 100% homozygous (genetically pure lines), making them ideal as parents for F1 Hybrids. There has been no genetic modification. Verdant now has a collection of Dura and Pisifera doubled haploids that span the genetic diversity of oil palm from which parents can be selected based on genetic contrasts (using Diversity Array Technology). The first F1 Hybrid crosses (Dura x Pisifera) were made in 2019 and field progeny trial testing started in 2021. Performance in the field is being monitored by a range of physiological tests, but ultimately on palm product yield per hectare plus commercially significant secondary traits, such as disease tolerance, will determine selection. The intention is to start commercial F1 Hybrid seed production in 2029. A phenomics nursery has been set up to correlate seedling physiological traits with yield with the aim of developing early indicators for yield potential and to screen for variation between crosses for 1) Ganoderma tolerance, 2) nutrient uptake, and 3) drought tolerance. Genotyping is also being deployed to identify and select heterotic combinations that result in hybrid vigour.

Bacterial community structure and predicted function in the rhizosphere of wild and cultivated date palms: Effects of Fertilizers on Composition and Functionality

This study investigated bacterial diversity in date palm rhizosphere and assessed the influence of different fertilizers on diversity using metagenomics. A total of 6356 Operational Taxonomic Units (OTUs) and 1164425 sequences were analyzed across 27 samples. The findings revealed variations in microbial community phylogeny among similar cultivars from different farms, except for the Khalas cultivar, suggesting minor influence of genotype on microbial community structure. Wild date palms exhibited more unique OTUs, in contrast, cultivated date palms had a higher number of OTUs and diversity. Moreover, different fertilizer treatments had varying effects on bacterial diversity. For example, organic and bio-organic fertilizers positively influenced specific bacterial groups, including delta-proteobacteria, acidobacteria-Gp3, Anaerolinaea, and Clostridia. Conversely, combining high concentrations of chemical fertilizers with other types did not show significant effects. Classes such as Bacilli, Nitrospira, Deltaproteobacteria, Spartobacteria, and Thermomacrobia exhibited high relative abundances in treatments with high chemical fertilizer concentrations. Our analysis revealed potential pathways related to carbon, nitrogen, phosphorus, phenol, sulfur, and antimicrobial compounds. Interestingly, these pathways and functions varied across different date palm cultivars. Our findings suggest that date palm cultivars shape the rhizosphere by selectively influencing bacterial communities consistently across other locations. These modulated bacterial communities can potentially provide enhanced benefits to the host. Importantly, this study was the first to investigate the soil bacterial diversity of wild date palms, giving valuable insights into the microbial community associated with this specific context.

Earliest fossil pollen records of endemic African Sclerosperma palms and the palaeoecological aspects of the genus

Palm diversity in present-day Africa is much less than in other tropical regions such as the Americas and Southeast Asia but comprises several endemic genera, including Sclerosperma. The origin and evolution of this small Arecaceae genus are still enigmatic, and every new fossil discovered helps fill the void in its palaeophytogeographic history. In this article, we report five different pollen morphologies assigned to Sclerosperma from the earliest Late Eocene (early Priabonian) of southeast Kenya, Africa. These pollen grains represent the earliest fossil records of Sclerosperma so far and add a new geographic region and time slot to the palaeophytogeographic history of this genus. The morphological variability observed in the fossil pollen suggests that the diversification within Sclerosperma was already underway by the onset of the Priabonian, c. 37 Ma. Detailed analysis of the distribution of the three extant Sclerosperma species shows that this genus occurs only under Equatorial/Tropical climates with MTCM ≥18 °C, such as fully humid Rainforest (Af), Monsoonal (Am), and winter dry Savannah (Aw) climates. Sclerosperma is also conservative when it comes to vegetation biomes and only occurs in three different but closely related biomes, the Tropical & Subtropical Moist Forests Biome, the Tropical & Subtropical Grasslands, Savannahs & Shrublands Biome, and the Mangroves Biome. No current outliners pinpoint to a wider ecological tolerance of this genus in the geological past. This suggests Sclerosperma to be an exceptionally reliable taxon for palaeoclimate estimations and when assigning palaeofloras to major vegetation biomes.

Morphometric Diversity of Date Palm (Phoenix Dactylifera L.) Cultivars from Gujarat Estimated by Fruit Characteristics

Morphometric Diversity of Date Palm (Phoenix Dactylifera L.) Cultivars from Gujarat Estimated by Fruit Characteristics

Native palms and trees mediate drought impacts on dry neotropical pastures

Abstract Dry forests are the most threatened biome across the global tropics. Despite their massive conversion into agricultural landscapes, local farmers often retain disperse trees and palms within grazing pastures. Understanding how on‐farm tree cover in the dry neotropics impacts the environmental and productive functions of pastures is key for biodiversity conservation and the development of climate‐resilient production systems. We studied tree composition of 23 dry cattle pastures in Yucatan, Mexico. We assessed the effects of palms, N2−fixing trees and non‐N2‐fixing trees on microsite environmental conditions, bare soil cover and the performance of grasses and woody plants in their understory during the dry and wet seasons of 2018 and 2019. We found that 45% of the total pool of tree species of the native dry forest is conserved in the pastures of Yucatan. Palms were the most abundant overstory functional group with a relative abundance of 45%, followed by N2‐fixing trees and non‐N2‐fixing trees with 33% and 22%. Palms and trees ameliorated the impact of seasonal drought on grasses but slowed down their recovery during the wet season. Palms had overall higher positive effects on grass greenness and height than N2‐fixing trees and non‐N2‐fixing trees and these effects were higher during the driest season. Palms decreased bare soil less than trees. Shrubs and tree seedlings tended to increase in the understory of all functional groups as the canopies of palms and trees became denser. Synthesis and applications. Climate warming and the alteration of precipitation regimes are expected to compromise pasture and cattle productivity worldwide. Our results show that fostering the maintenance of a diversity of native palms and trees has positive effects on the functioning of cattle pastures, especially during dry periods. A larger appreciation and understanding of the facilitative effects of remnant palms and trees on pastures during seasonal droughts may help developing more climate‐resilient livestock systems that maintain productivity during dry conditions while contributing also to tree biodiversity conservation.

Phenotypic diversity of date palm varieties (Phoenix dactylifera L.) from southwest Algeria estimated by fruit characteristics

<p class="042abstractstekst">This study aimed to identify the genetic diversity of date palm (<em>Phoenix dactylifera</em> L.) in the southwest of Algeria (wilaya of Adrar), as part of the Algerian date palm varieties conservation. The morphological characterization was adopted in terms of quality and quantity of 26 varieties. The main results showed a considerable genetic diversity of date palms in this agricultural territory. 7 cultivars counted in danger of extinction. The cluster analysis brought out significant differences between qualitative and quantitative traits. However, the cultivars of ‘Deglet Talmine’, ‘Maatouk’, and ‘Timidouele’ produced dates of high quantitative traits, however, of different qualitative traits. Also, some relationships were observed within clusters for other varieties. A variety named ‘Khalt’ was able to produce dates better than many cultivars. This work would help to know the focal traits of the plant genetic resources of date palm and preserve that are in extinction.</p>

Phenotypic diversity of date palm varieties (Phoenix dactylifera L.) from southwest Algeria estimated by fruit characteristics

This study aimed to identify the genetic diversity of date palm (Phoenix dactylifera L.) in the southwest of Algeria (wilaya of Adrar), as part of the Algerian date palm varieties conservation. The morphological characterization was adopted in terms of quality and quantity of 26 varieties. The main results showed a considerable genetic diversity of date palms in this agricultural territory. 7 cultivars counted in danger of extinction. The cluster analysis brought out significant differences between qualitative and quantitative traits. However, the cultivars of ‘Deglet Talmine’, ‘Maatouk’, and ‘Timidouele’ produced dates of high quantitative traits, however, of different qualitative traits. Also, some relationships were observed within clusters for other varieties. A variety named ‘Khalt’ was able to produce dates better than many cultivars. This work would help to know the focal traits of the plant genetic resources of date palm and preserve that are in extinction.

Genetic diversity of Moroccan date palm revealed by microsatellite markers.

The genetic diversity between 23 Moroccan date palm cultivars collected from the National Palm Collection at the INRA (National Agricultural Research Institute) experimental field in Zagora was assessed using SSR markers that are specifically designed for date palm. Among the 16 tested SSR, 13 were successfully amplified, and were selected to carry out this study. 208 bands were amplified, ranging from 10 to 25 bands per cultivar with an average of 16 alleles per cultivar. The value of heterozygosity of the studied markers ranged from 0.11 to 0.30. The pairwise genetic distances between those cultivars ranged from 0.06 to 0.46. The hierarchical cluster analysis distributed the 23 genotypes into four different groups of one to ten cultivars.

What lies behind a fruit crop variety name? A case study of the barnī date palm from al‐‘Ulā oasis, Saudi Arabia

Societal Impact StatementThe oasis of al‐‘Ulā is subject to a vast development operation by the central government of the Saudi monarchy. Agriculture is not strictly speaking the first objective of this initiative, the emphasis being on tourism and thus on the vast historical heritage and landscape qualities of the region. Nevertheless, agriculture and, in particular, phoeniculture remain the main resource for the inhabitants. Characterizing the local date palm agrobiodiversity is key to the sustainable development of oases. In al‐‘Ulā, documenting indigenous knowledge about the locally predominant barnī variety and characterizing its genetic integrity and mode of propagation represents the essential leverage needed by farm development project planners to develop local production.Summary Understanding how farmers name and categorize their crops in relation to the way they are propagated is critical for a proper assessment of agrobiodiversity. Yet, indigenous knowledge is often overlooked in genetic studies, which may result in an underestimation of crop diversity, thereby preventing its conservation and mobilization for developing sustainable agroecosystems. Here, we focus on the barnī date palm variety, a local elite variety of al‐‘Ulā oasis, Saudi Arabia. We conducted an ethnobotanical survey on local phoeniculture practices and generated whole‐genome data to determine whether or not barnī palms are exclusively clonally (vegetatively) propagated. Further, we contrasted the genomes of barnī and two other palms from al‐‘Ulā with 112 Phoenix spp. to provide an initial insight into date palm diversity in this oasis. The survey reveals that the dates of the barnī palm bear distinct names, depending on their quality. Results show that barnī is a true‐to‐type cultivar, indicating clonal propagation by offshoots with name maintenance, even between distinct cultivating situations in al‐‘Ulā and a nearby oasis. Nonetheless, it is distinct from the prominent barnī cultivated in Oman. Its ancestry is comparable to other West Asian date palms, but another palm from this oasis shows influence from North Africa. What lies behind the cultivar name barnī in al‐‘Ulā and further afield in the Arabian Peninsula has been deciphered through the key disciplinary combination of social anthropology and genetics. Future studies will provide additional insights into the original genetic make‐up of this millennia‐old oasis.

Recent advances in date palm genomics: A comprehensive review.

As one of the oldest fruit trees of the Arabian peninsula, other Middle-Eastern countries, and also North Africa, the date palm (Phoenix dactylifera L.), is highly significant for the economy of the region. Listed as part of UNESCO’s Intangible Cultural Heritage of Humanity, the date palm is believed to be the first tree cultivated by human beings, and was probably first harvested for its fruit nearly 7,000 years ago. Initial research efforts in date palm genetics focused on understanding the genetic diversity of date palm germplasm collections and its phylogenetic history, both important prerequisites for plant improvement. Despite various efforts, the center of origin of the date palm is still unclear, although genomic studies suggest two probable domestication events: one in the Middle East and the other in North Africa, with two separate gene pools. The current review covers studies related to omics analyses that have sought to decipher the present genetic diversity of the date palm. With advances and cost reductions in sequencing technologies, rapid progress has been made in the past few years in date palm genomics research. Along with organellar genomes, several reference genomes of the date palm are now available. In addition, several genotypes have been re-sequenced, either to detect single nucleotide polymorphisms (SNPs), or to study domestication and identification of key genes/loci associated with important agronomic traits, such as sex, fruit color, and sugar composition. These genomics research progress has paved the way to perform fast-track and precise germplasm improvement processes in date palm. In this study, we review the advances made in the genetics and genomics of the date palm so as to strategize targeted crop improvement plans for marginal areas of the Middle Eastern peninsula, North Africa, and other parts of the world.

Varietal Diversity of Date Palm (Phoenix dactylifera L.) in South-western Oases of Algerian Sahara: A Review

We designate here the name designate ‘oasis’ (Wit in Egyptian, Wah in Copte, Waha in Arabic et in Persian, Neve in Hebrew, et Ouasis in Greek), points located in the desert and which are distinguished from the surrounding environment by more or less abundant vegetation. The date palm (Phoenix dactylifera L.) is the backbone of the oasis and it is the one that must be protected. This review has the objective toexplain the typological and agroecosystem of saoura oasis and its contraints. The data obtained in this study are based on statistics from national and international institute like CRSTRA, ONID, ITDAS and RADDO and also from surveys and prospecting missions with the help of farmers who have given us all the routes carried out in their fields and the main constraints that affect this kind of crop. The data obtained showed that the oasis has certain pedoclimatic, geological and hydrogeological properties specific to the arid environment. The oasis agrosystem studied (saoura) has certain specificities compared to others, such as the absence or presence of certain constraints on the date palm such as the bayoud and the date moth. Regarding varietal diversity, ‘Feggous and H-mira’, these are the most important varieties in Saoura region, but are sensitive to certain constraints such as Bayoud, which requires the selection of new resistant varieties.

Pinangapalms revisited 20 years on: what can changes inPinangaspecies populations tell us about rainforest understory palm persistence?

AbstractBorneo is the centre of diversity of the palm genusPinanga. At least 13 understory species have been recorded in the Ulu Temburong National Park in Brunei, but little is known of their persistence. Changes in populations ofPinangaunderstory palms may be indicative of more widespread changes due to climate change, such as changes in rainfall, which may be important for the palm diversity in the protected area. However, we know little about the population dynamics of these palms, how persistent their populations are or if they behave similarly over long time frames. In 1998, populations of five co-occurring species ofPinangaat several locations in the Ulu Temburong National Park were documented. This project aimed to undertake a comprehensive resurvey of the original fivePinangapalm species populations in order to assess if they showed similar population changes across sites and species after two decades. Overall, most species maintained their population size in the surveyed region but not consistently among sites, and one species significantly declined in abundance. There was considerable variation in population growth rate (R) within and among species and sites that was significantly correlated with density and the percentage of multi-stemmed plants. There was evidence of pulsed recruitment in some species and or sites rather than steady or exponential patterns of population growth.

Large mammalian herbivores modulate plant growth form diversity in a tropical rainforest

Abstract The world’s terrestrial biomes are broadly classified according to the dominant plant growth forms that define ecosystem structure and processes. Although the abundance and distribution of different plant growth forms can be strongly determined by factors such as climate and soil composition, large mammalian herbivores have a strong impact on plant communities, thus defaunation (the local or functional extinction of large animals) has the potential to alter the compositional structure of plant growth forms in natural ecosystems. Tropical rainforests sustain a high diversity of growth forms, including trees, palms, lianas, shrubs, herbs and bamboos, all of which play important ecosystem functions. Here, we experimentally evaluate how large mammalian herbivores affect the dominance, diversity and coexistence of these major tropical forest plant growth forms, by monitoring communities of saplings on the understorey in 43 paired exclusion plots in a long‐term replicated exclusion experiment in the understorey of the Atlantic forest of Brazil. Over the course of 10 years large herbivore exclusion decreased diversity among growth forms, increased the absolute abundance of palms and trees (22% and 38% respectively) and increased the diversity of species within these two groups, to the detriment of other growth forms. Furthermore, all pairwise relationships between growth forms were positive on plots where herbivores had access, whereas several strong negative relationships emerged in plots where herbivores were excluded. This occurred despite strong background directional temporal trends affecting plant communities in both experimental treatments across the region. Synthesis. Our work indicates that the defaunation alters growth form dominance by favouring palms and trees while eroding diversity among growth forms and coexistence on a temporal scale. Large herbivore mammals promote diversity among growth forms, preventing the hyper‐dominance of trees and palms, yet without supressing the diversity of species within growth forms. We argue that large herbivore mammals affect growth forms through several non‐mutually exclusive mechanisms, including herbivory, seed dispersal and physical disturbance, as well as differential effects linked to the morphological and physiological adaptations of growth forms. We conclude that defaunation might lead to profound impacts on important ecosystem functions underpinned by growth form diversity, and result in vertical and horizontal structural simplification of tropical rainforests.

Genetic Diversity and Population Structure of Doum Palm (Hyphaene compressa) Using Genotyping by Sequencing.

Doum palm (Hyphaene compressa) is a perennial economic plant primarily growing in Kenya’s Arid and Semi-Arid Lands (ASALs). It is heavily relied upon for food, animal feed, construction materials and medicine, making it an ideal plant for resource sustainability. However, the limited information on its genetic resources has hindered its breeding and conservation studies. This study used the genotyping by sequencing approach to identify Single Nucleotide Polymorphisms. These SNPs were further used to assess the genetic diversity and population structure of 96 H. compressa accessions from Coastal, Northern and Eastern ASAL regions of Kenya using two approaches; reference-based and de novo-based assemblies. STRUCTURE analysis grouped the sampled accessions into two genetic clusters (Cluster 1 and Cluster 2). Cluster 1 included accessions from the Northern region, whereas Cluster 2 included all accessions from Eastern and Coastal regions. Accessions from Kwale (Coastal) had mixed ancestry from both Cluster 1 and Cluster 2. These STRUCTURE findings were further supported by principal components analysis, discriminant analysis of principal components and phylogenetic analysis. Analysis of molecular variance indicated greater genetic variation within populations (92.7%) than among populations (7.3%). An overall FST of 0.074 was observed, signifying moderate genetic differentiation among populations. The results of this study will provide information useful in breeding, marker-assisted selection and conservation management of H. compressa.